Pre-purchase questions

Roger Studer

I'm looking hard at the EXOS2-GT w/PMC-8. I have never had a GOTO mount of any kind. I like everything I have seen and read about this mount except for the lack of a hand controller at the telescope. My plan would be to have the mount hooked up to my laptop about 25 feet from the telescope. I would select my next target and slew to it from the laptop, walk to the scope and if not centered in the eyepiece how would I adjust it? It just seems natural to me to look through the eyepiece while adjusting the mount. I don't see a way to do that with this setup. Even if using a tablet at the scope, instead of my laptop 25 feet away, isn't it difficult to adjust the mount, while looking through the eyepiece, without the feel of the buttons of a hand controller? It would seem to me that you would need to look at the tablet to find the buttons.

Does anyone find this to be a major drawback in using the system? Like I said I really don't have experience with GOTO mounts but just trying to think this through before pulling the trigger. How hard would it have been to add an auxiliary port to the brain box for an optional hand controller? Would it be possible for the end user to add a port for simple 4 directional movement? It really wouldn't need to be any smarter than left, right, up and down.

Any input would be greatly appreciated.


Hi Astroled,

The ExploreStars application running on a tablet is designed to be the hand controller and there are a number of features that help recreate the feedback and response that you would get from a traditional hard-key hand controller. The main one is the near instantaneous response when hitting the tablet from the mount. The mount will move immediately and then ramp up to the selected speed. Also, there is on the left hand side of the application the virtual joystick that can be used as an alternative to the up, down, left, right buttons. You can place your thumb or finger on the virtual joystick and drag it around, the further from the center you drag it, the faster the mount moves. So those are the two main features that once you get used to them, will provide the performance you expect from a hand controller.

The auto-guider port can provide a dumb switch input for a switch box if you would like to use that, but it is currently limited to moving the mount at a fraction of the sidereal rate for auto-guiding. We use a simple switch input box when calibrating the ST4 port in fact. The ST4 port is a strictly hardware function and is completely independent of the ExploreStars application and does not currently interact with the application. I am considering some firmware updates that will allow you to configure the ST4 port speeds to faster rates, but this will require some testing to make sure that the user would not inadvertently break the standard ST4 port auto-guiding function. At the end of the day, anything is possible, but it is difficult to make a controller that will be everything for everybody.

Thanks for your question!

Jerry Hubbell
Director Electrical Engineering
Explore Scientific, LLC.

Roger Studer

Hi Jerry,

Thank you for your response. The part about using the ST4 port for attaching a dumb switch box is very interesting to me. It wouldn't need to provide slewing speed, obviously, but the current "at a fraction of the sidereal rate" might be a little too slow, would only need to be fast enough to fine tune the position in the eyepiece and I'd be happy as a clam. When you say you are considering a firmware update to cover that aspect what are you really saying, it might not ever actually happen or it might not be available for a considerable amount of time or go ahead and buy the mount you can count on having that functionality in a reasonable amount of time? Also is it possible that your dumb box might be made available as an optional accessory? 

I suppose I might get use to using the app on a tablet at the telescope, but I'm the kind of guy that can type fine as long as I'm looking at the keyboard. Just can't quite see myself finding the right location on the screen without looking at it. I can do the buttons on my TV remote in the dark because I've learned where the important ones are in relation to each other, if that makes any sense. But then I guess if I'm using the app, at the telescope, for more than just fine tuning an object in the eyepiece, I'm going to want to be looking at the tablet anyway. 

Then there is also the question of how looking at the tablet screen is going to affect a persons night vision, I know that, with my laptop, even when my programs are switched to night vision mode and the screen brightness is turned all the way down it seems awfully bright and must be having an affect on my night vision.

I realize that when coming out with a product such as this you can't expect to satisfy everyone. I can appreciate that and I think that the modifications you have made to the old LDX75 mount offer an excellent mount at an excellent price point. I'm just not sure whether to purchase the basic mount and try a Goto DIY upgrade or to save the grief and go with the PMC-8. I would appreciate any additional input you might be willing to share.